This experiment is a continuing project examining if tolerance to ethanol following chronic exposure has a large genetic influence. Over the past year, 2 selected generations of both replicate lines (400 rats in total) have been tested and bred for the degree of tolerance to ethanol. Presently, the third generation for two lines have been tested (100 rats). Based on the results of previous studies using an ethanol related trait as the phenotype, selected lines do not clearly start to separate until the fourth or fifth generation. Thus, this project is still in the early stages, and an evaluation of the success of the project is premature. However, there does appear to be a decrease in the amount of variance in the degree of tolerance acquired across the three generations tested as well as a tolerance to length of time the animals have lost their righting reflex.